Gas-sparged hydrocyclones have become increasingly effective and popular for use in de-inking recycled paper pulp, removing "stickies" during pulp recycling, and for a number of other purposes. Basic features of the gas-sparged hydrocyclone for these purposes are shown in U.S. Pat. No. 5,173,177, the disclosure of which is hereby incorporated by reference herein. In conventional gas-sparged hydrocyclones, such as sold by Kamyr, Inc. of Glens Falls, N.Y., under the trademark GSC.RTM., an orifice is defined inside the cyclone body between a plug and the surrounding cylindrical surface of the cyclone body. The flow rate of the hydrocyclone is controlled by adjusting the size of that orifice by movement of the plug, thereby controlling many of the operational parameters of the equipment.
The equipment for automatically regulating the orifice should the cyclone become clogged, such as shown in said U.S. Pat. No. 5,173,177, has not been successfully implemented, and the conventional GSC.RTM. hydrocyclones have an inconvenient mechanism for adjusting the orifice. In the conventional mechanisms, the hydrocyclone must be shut down before the orifice can be adjusted, a rubber boot must be removed so that a plug providing adjustment can be accessed, and a threaded cylinder must be rotated before the plug position can be adjusted. Then the rubber boot must be replaced before operation of the hydrocyclone can be initiated again.
According to the present invention, a hydrocyclone is provided with an effective mechanism and method for varying the accepts orifice size. The mechanism and method according to the present invention is convenient and inexpensive, and advantageously allows operation of the hydrocyclone as the orifice adjustment is being made. The invention thus results in a significant improvement in the operability and convenience of conventional hydrocyclones, such as GSC.RTM. hydrocyclones.
According to one aspect of the present invention, a hydrocyclone is provided having the following conventional components: A substantially hollow body having first and second ends and a wall disposed about an axis, and axially elongated. An inlet for introducing a suspension into the hollow body at the first end thereof so that the suspension flows in a vortex within the hollow body. A first outlet for withdrawing flowable material from adjacent the axis at the first end of the body. A porous surface of revolution disposed within the hollow body wall generally symmetrical with the axis, a plenum defined between the body wall and the porous surface of revolution. At least one fluid introduction opening for introducing fluid into the plenum to pass through the porous body of revolution into the vortex. A second outlet for withdrawing suspension from adjacent the second end of the body, the body having an interior surface adjacent the second outlet. And, a plug mounted adjacent the second end of the body, and having an exterior surface portion thereof positioned interiorly of the body interior surface, an orifice defined between the body interior surface and the plug exterior surface portion. According to the present invention, the hydrocyclone also includes mechanical means accessible from a position exteriorly of the hollow body for directly linearly moving the plug with respect to the body interior surface adjacent the second outlet to adjust the size of the orifice, the mechanical means operable even when the hydrocyclone is running with suspension fed to the inlet and fluid to so the fluid introduction opening.
The mechanical means preferably advantageously comprises the following elements: A first pin mounted to the plug. A first link having first and second ends and pivotally connected at the first end thereof to the first pin. A second pin. A second link having first and second portions. A shaft mounted for rotation with respect to the plug about an axis of rotation, and having a drive portion extending exteriorly of the hydrocyclone. The first link pivotally connected at the second end thereof to the second pin. The second link pivotally connected at the first portion thereof to the second pin. The second link rigidly connected at the second portion thereof to the shaft. And, a guide insuring linear movement of the plug in response to rotation of the shaft drive portion.
The hydrocyclone may further comprise: A third link rigidly connected to the drive portion of the shaft exteriorly of the hydrocyclone, and a handle connected to the third link facilitating pivotal movement of the third link to thereby effect rotation of the about the axis of rotation, and indexing means may be operatively connected to the third link for holding the third link in the position to which it has been moved. The indexing means typically includes human-readable indicia thereon relating various positions of the third link to the sizes of the orifices corresponding to the various positions of the third link.
Preferably, the indexing means comprises the following elements: A plate operatively stationarily mounted to the hollow body and having a plurality of openings therein. An index pin dimensioned to fit within the openings in the plate. And an opening in the third link, remote from the shaft, through which the index pin passes and with respect to which the index pin is movable from a first position in which the index pin is not within an opening in the plate and therefore the third link is pivotal, to a second position in which the index pin is within an opening in the plate and therefore the third link is not pivotal.
The plug may have a wide variety of configurations and still be eminently functional. In one embodiment of the plug according to the invention, the plug exterior surface comprises a tapered truncated cone, which cooperates with a substantially cylindrical interior surface of the hollow body. The plug may have a hollow interior, an open bottom to the hollow interior, and a closed top. The first pin may be mounted within the hollow interior of the plug along with at least part of the first lever. The shaft is exterior of the plug hollow interior and closer to the open bottom than to the closed top. The guide may comprise an interior surface of the plug defining the plug hollow interior, and a tube operatively stationarily mounted to the body. The shaft may be journalled by the tube for rotation, and the first and second links are typically disposed within the tube.
Instead of a manual drive provided by the third link/handle arrangement described above, the drive portion of the shaft may be connected to a stepper motor for effecting rotation thereof. The stepper motor may be controlled by a manual switch for effective drive (in either of two directions) thereof, or it may be controlled by a pressure or flow rate control means which operates the motor automatically in a response to a particular pressure or flow rate within the hollow body of the hydrocyclone.
The mechanical drive provided by the present invention is simple, inexpensive, and sturdy, with little to go wrong over time, while still providing positive adjustment of the orifice size including when the hydrocyclone is running.
The invention also relates to a method of operation a hydrocyclone. The method comprises the following steps:
(a) Introducing a paper pulp suspension having a consistency of about 4% or less into the inlet so that the suspension flows in a vortex with the hollow body. (b) Withdrawing accepts flowable material from the first outlet. (c) Introducing a fluid into the fluid introduction opening to pass through the porous body of revolution into the vortex. PA1 (d) Withdrawing suspension through the second outlet. And (e) from a position exteriorly of the hollow body, while steps (a) through (d) are being practiced, directly mechanically linearly moving the plug with respect to the body interior surface to adjust the size of the orifice.
It is the primary object of the present invention to provide a convenient and inexpensive mechanical drive and method for varying the size of the accepts orifice for a hydrocyclone. This and other objects of the invention will become clear from an inspection of the detailed description of the invention and from the appended claims.